An apparatus that handles paper sheets such as banknotes includes a paper-sheet recognition apparatus incorporated therein, which recognizes input banknotes of various denominations and authenticates input banknotes. In the paper-sheet recognition apparatus, it is necessary to read the image of an input paper sheet, and thus the paper-sheet recognition apparatus includes a mechanism therefor. As a conventional mechanism that reads images of paper sheets, there has been proposed a mechanism provided with luminous bodies such as light emitting diodes (LEDs) of a plurality of types that emit lights of different wavelengths, in which the LEDs of a plurality of types that emit light of a different wavelength are simply made to illuminate alternately, to read a reflection image or a transmission image obtained by illuminating by an image sensor (for example, see Patent Documents 1 and 2).
FIG. 1 is an example of line data read by a conventional paper-sheet recognition apparatus. FIG. 1 exemplifies a case that luminous bodies that emit infrared light and green wavelength visible lights are used to acquire a reflection image and a transmission image for each light. As shown in FIG. 1, conventionally, a banknote is read by repeating a cycle of transmitted infrared light→transmitted green→reflected infrared light→reflected green→two areas undetected. Further, conventionally, a banknote is carried by 0.25 mm/scan and is scanned with lights of four different wavelengths (transmitted lights of two wavelengths and reflected lights of two wavelengths), and because there is a state that there is no action for two scans, resolution per wavelength is 16.9 dpi (=1×25.4 mm/(0.25 mm×6)).
Patent Document 1: Japanese Utility Model Application Laid-open No. S64-7463
Patent Document 2: Japanese Patent Application Laid-open No. H9-212706